Using Antenna Reflection Coefficients to Detect Events in a Gaming Environment

ABSTRACT

A gaming table includes a network analyzer. The network analyzer detects antenna reflection coefficients faster than RFID tags can be read, enabling game state information to be monitored quickly. The network analyzer detects changes in the reflection coefficients that result from movements of a human appendage, enabling the system to change game states in response to the detected hand movements.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.14/942,329 for “Using Antenna Reflection Coefficients to Detect Eventsin a Gaming Environment” filed Nov. 16, 2015, which claims the benefitof U.S. Provisional App. No. 62/092,744 for “Using Antenna ReflectionCoefficients to Detect Events in a Gaming Environment” filed Dec. 16,2014; both of which are incorporated herein by reference.

BACKGROUND

The present invention relates to gaming, and in particular, to detectingevents in a gaming environment using antenna reflection coefficients.

Unless otherwise indicated herein, the approaches described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

A gaming environment may implement radio-frequency identificationtechnology to track gaming tokens or other objects related to the games.For example, U.S. Pat. No. 8,432,283 describes a gaming table withmultiple antennas, where each antenna is associated with a betting spoton a gaming table. Gaming tokens (that contain radio frequencyidentification (RFID) tags) may be placed on a betting spot and may beread by an RFID reader using the antenna associated with that bettingspot.

SUMMARY

One issue with existing systems is that they are often require manualintervention to detect and process events. One common way to performevent monitoring is for a person to watch a gaming table via a remotecamera.

Given the above, embodiments are directed toward improving the abilityof the system to detect and process events.

According to an embodiment, a system detects events in a gamingenvironment. The system includes an antenna, a network analyzer device,and a control device. The antenna is positioned on a gaming table. Thenetwork analyzer device is coupled to the antenna and is configured todetect reflection coefficients that are associated with the antenna. Thereflection coefficients change as a human appendage interacts with theantenna. The control device is coupled to the network analyzer deviceand is configured to control a game state related to the gaming table inthe gaming environment in response to the change in the reflectioncoefficients.

The reflection coefficients may change from a first state to a secondstate when the human appendage moves from outside the antenna to insidethe antenna, or vice versa. The control device may control the gamestate according to the reflection coefficients switching between thefirst state and the second state.

The human appendage may interacts with the antenna by passing over theantenna on the gaming table.

The reflection coefficients may also change as both the human appendageand an object interact with the antenna, where a gaming object includesthe object. The object may be a metallized layer in a playing card, or atuned circuit in a dealer wristband.

The system may further include a radio frequency identification (RFID)reader device that is configured to selectively energize the antenna andto read identifiers of RFID tags that are nearby to the antenna. Thecontrol device is configured to control the game state in response tothe change in both the reflection coefficients and the identifiers.

The antenna may have a single loop, rectangular shape or a double loop,figure eight shape.

The control device may store a baseline set of reflection coefficients,where the control device periodically controls the network analyzer toacquire a new baseline set of reflection coefficients, and where thecontrol device updates the baseline set of reflection coefficients withthe new baseline set of reflection coefficients.

The network analyzer device may operate between 13 and 14 MHz.

The game state may be one of a plurality of game states, and the antennamay be one of a number of antennas positioned on the gaming table. Theantennas are respectively associated with a number of locations. Thecontrol device is configured to associate each of the locations with acorresponding one of the game states in response to the change in thereflection coefficients for a corresponding one of the antennas. Forexample, a card dealt to Position 1 changes the game state to one statefor Position 1, and a card dealt to Position 2 changes the game state toanother state for Position 2.

According to an embodiment, a method detects events in a gamingenvironment. The method includes detecting reflection coefficients thatare associated with an antenna positioned on a gaming table. Thereflection coefficients change as a human appendage interacts with theantenna. The method further includes controlling a game state related tothe gaming table in the gaming environment in response to the change inthe reflection coefficients.

The method may further include selectively energizing the antenna, andreading identifiers of RFID tags that are nearby to the antenna, wherecontrolling the game state comprises controlling the game state inresponse to the change in both the reflection coefficients and theidentifiers.

The method may further include storing a baseline set of reflectioncoefficients, periodically acquiring a new baseline set of reflectioncoefficients, and updating the baseline set of reflection coefficientswith the new baseline set of reflection coefficients.

According to an embodiment, a method detects events in a gamingenvironment. The method includes detecting reflection coefficients thatare associated with antennas positioned on a gaming table. The antennasare respectively associated with locations on the gaming table. Thereflection coefficients change as a human appendage interacts with theantennas. The method further includes controlling game states related tothe gaming table in the gaming environment in response to the change inthe reflection coefficients. Each of the locations is associated with acorresponding one of the game states in response to the change in thereflection coefficients for a corresponding one of the antennas.

The following detailed description and accompanying drawings provide afurther understanding of the nature and advantages of embodiments of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system 100 for detecting events in agaming environment.

FIGS. 2A, 2B, 2C, 2D and 2E are polar diagrams showing examples ofreflection coefficient measurements by the network analyzer 106 (seeFIG. 1) for one of the antennas 122.

FIG. 3 is a block diagram of a system 300 for detecting events in agaming environment.

FIG. 4 is a block diagram of a system 400 for detecting events in agaming environment.

FIG. 5 is a block diagram of a system 500 for detecting events in agaming environment.

FIG. 6 is a block diagram of a seat board 600.

FIG. 7 is a block diagram of a seat board 700.

FIG. 8 is a block diagram of a network analyzer 800 and relatedcomponents.

FIG. 9 is a block diagram of a network analyzer 900 and relatedcomponents.

FIG. 10 is a flowchart of a method 1000 of detecting events in a gamingenvironment.

FIG. 11 is a flowchart of a method 1100 of detecting events in a gamingenvironment.

FIG. 12 is a block diagram of a detection system 1200.

FIG. 13 is a block diagram of a detection system 1300.

FIG. 14 is a polar diagram showing an example of reflection coefficientmeasurements by the detection system 1200 (see FIG. 12) when anappendage is not present.

FIG. 15 is a polar diagram showing an example of reflection coefficientmeasurements by the detection system 1200 (see FIG. 12) when anappendage is present.

FIG. 16 is a flowchart of a method 1600 of detecting events in a gamingenvironment.

DETAILED DESCRIPTION

Described herein are techniques for using antenna reflectioncoefficients to detect actions on a gaming table. In the followingdescription, for purposes of explanation, numerous examples and specificdetails are set forth in order to provide a thorough understanding ofthe present invention. It will be evident, however, to one skilled inthe art that the present invention as defined by the claims may includesome or all of the features in these examples alone or in combinationwith other features described below, and may further includemodifications and equivalents of the features and concepts describedherein.

In the following description, various methods, processes and proceduresare detailed. Although particular steps may be described in a certainorder, such order is mainly for convenience and clarity. A particularstep may be repeated more than once, may occur before or after othersteps (even if those steps are otherwise described in another order),and may occur in parallel with other steps. A second step is required tofollow a first step only when the first step must be completed beforethe second step is begun. Such a situation will be specifically pointedout when not clear from the context.

In this document, the terms “and”, “or” and “and/or” are used. Suchterms are to be read as having an inclusive meaning. For example, “A andB” may mean at least the following: “both A and B”, “at least both A andB”. As another example, “A or B” may mean at least the following: “atleast A”, “at least B”, “both A and B”, “at least both A and B”. Asanother example, “A and/or B” may mean at least the following: “A andB”, “A or B”. When an exclusive-or is intended, such will bespecifically noted (e.g., “either A or B”, “at most one of A and B”).

FIG. 1 is a block diagram of a system 100 for detecting events in agaming environment. In FIG. 1, the dotted connectors indicate the flowof control information, and solid lines indicate the flow of data or theflow of both data and control information. Note that such illustrationof a connector as either dotted or solid is provided for clarity ofdescription, and does not necessarily indicate that the connection isexclusive to either control information or data.

The system 100 includes a seat board 102, a control board 104, a networkanalyzer device 106 (also referred to as the network analyzer 106), aradio frequency identification (RFID) reader device 108 (also referredto as the RFID reader 108), and a computer 110. The seat board 102,control board 104, network analyzer 106, and RFID reader 108 may becomponents of a gaming table 120. The computer 110 may connect to thegaming table 120 with a local area network (LAN) connection, e.g.Ethernet LAN (Institute of Electrical and Electronics Engineers IEEE802.3 standard). The computer 110 may be located remote from the gamingtable 120, and may connect to multiple gaming tables (not shown). Thecomputer 110 may connect to other computers (not shown) thatcollectively perform the functions of the computer 110 discussed below.

The seat board 102 is generally located on a top surface of the gamingtable 120 and generally functions as the area in which gaming objectsare placed. Gaming objects include gaming tokens, cards, tiles, dice,etc. The seat board 102 includes one or more antennas 122 that couple toRFID tags in the gaming objects as the gaming objects are placed on,moved, or removed from the area associated with the seat board 102. (Oneof the antennas 122 may be referred to as a selected antenna 122, aparticular antenna 122, or a corresponding antenna 122.) Each of theantennas 122 is associated with a corresponding area on the gaming table120, allowing the system 100 to energize a particular antenna and todetect the gaming objects that are located at the area associated withthat particular antenna. The term “betting area” may be used to refer tothe area on the seat board 102 in which gaming tokens are placed whenmaking or paying out bets. The term “stash area” may be used to refer toan area on the seat board 102 in which gaming tokens not currentlyinvolved in the game play may be placed. The seat board 102 may includea player stash area that is associated with a player (or other patron ofthe gaming environment), or a dealer stash area that is associated witha dealer (or other employee of the gaming environment). The term“geofence” (or “geofencing”) may be used to refer to an area on the seatboard 102 that detects a gaming object related to a game state. Thenumber, size, shape, and location of the antennas 122 may be adjusted asdesired, for example to increase the number of betting areas. The seatboard 102 may be implemented using a printed circuit board that has theantennas 122 or other circuit structures printed or attached.

The control board 104 generally controls the interaction between theseat board 102 and the network analyzer 106, the RFID reader 108, andthe computer 110. The control board 104 controls a switch 124 usingswitch control information 123. The switch 124 selectively connects oneof the network analyzer 106 and the RFID reader 108 to the seat board102 for the transmission of radio frequency (RF) energy. The switch 124may be implemented with a multiplexer circuit. Alternatively, the switch124 may be a component of the seat board 102.

The control board 104 also sends antenna address information 125 to anantenna selection circuit 126, to control which of the antennas 122 isselectively connected to the switch 124. The antenna selection circuit126 may be implemented with a multiplexer circuit.

The control board 104 also interacts with the computer 110 to receivethe antenna address information 125, and to return the measurement datagenerated by the network analyzer 106 for the selected antenna 122. Thecontrol board 104 may be implemented using a printed circuit board thathas the network analyzer 106, a processor, a memory, or other circuitstructures printed or attached.

The network analyzer 106 generally measures the reflection coefficientof a selected antenna 122 by energizing the selected antenna 122 withradio frequency (RF) energy. The reflection coefficient may also bereferred to as the reflectance. The term “reflection coefficients” maybe used to refer to more than one reflection coefficient, for examplethe reflection coefficients at different times for a single antenna, thereflection coefficients at different frequencies for a single antenna,or the reflection coefficients for more than one antenna. The term“reflection coefficients” may also be used to refer to the components ofa single reflection coefficient, such as the rho and theta values (or Iand Q values, etc.) corresponding to a single reflection coefficientmeasurement.

As gaming objects interact with (also referred to as “couple to” or“couple with”) a particular antenna 122, the reflection coefficient maychange. For example, when the network analyzer 106 sends radio frequencyenergy to a selected antenna 122 that has no gaming objects coupledtherewith, a first reflection coefficient results. When one or moregaming objects then come into the vicinity of the selected antenna 122(e.g., by being placed on the betting spot associated with the selectedantenna 122), a second reflection coefficient results when the networkanalyzer 106 sends radio frequency energy to the selected antenna 122due to the gaming objects coupling with the selected antenna 122. Whensome, but not all, of the gaming objects are removed from the vicinityof the selected antenna 122 (e.g., by being removed from the bettingspot), a third reflection coefficient results when the network analyzer106 sends radio frequency energy to the selected antenna 122 due tothere being fewer gaming objects coupling with the selected antenna 122.By comparing the reflection coefficients, the system 100 can detectevents such as gaming objects being placed on, removed from, orotherwise interacting with the gaming table 120. The network analyzer106 may be implemented using a circuit such as a network analyzer chip.

The RFID reader 108 generally reads the RFID tags in gaming objects thatare in the vicinity of a selected antenna 122 by energizing the selectedantenna 122 with radio frequency (RF) energy. In one implementation, theRFID reader 108 generates the energy at 13.56 MHz. Each of the RFID tagsthat receives the energy responds with its corresponding uniqueidentifier. The RFID reader 108 then sends the received identifiers tothe computer 110.

The computer 110 generally receives the reflection coefficients obtainedby the network analyzer 106, receives the identifiers of the gamingobjects read by the RFID reader 108, and performs further processingbased on the reflection coefficients or the identifiers. The computer110 includes various databases 130. The databases 130 may include areflection coefficients database, a tag database and a game rulesdatabase.

The computer 110 uses the reflection coefficients database to store setsof reflection coefficients in order to detect when they change for aselected antenna 122. For example, for a selected antenna 122, thereflection coefficients database may store a baseline set (e.g., whichcorresponds to no gaming objects near the selected antenna 122); thecomputer 110 uses the baseline set to compare to the current set for theselected antenna 122, in order to detect that the selected antenna is nolonger at baseline (e.g., gaming objects are now coupling to theselected antenna 122). As another example, for a selected antenna 122,the reflection coefficients database may store a previous set (e.g.,which corresponds to a previous measurement of the reflectioncoefficients for the selected antenna 122); the computer 110 uses theprevious set to compare to the current set for the selected antenna 122,in order to detect the change in the reflection coefficients. Once thecomputer 110 detects the change in the reflection coefficients for aparticular antenna 122, the computer 110 controls the RFID reader 108 toperform a read on that particular antenna 122.

The computer 110 uses the tag database to verify that the identifiersreceived from the RFID reader 108 correspond to valid tags, and tocorrespond those identifiers to other information such as the value ofthe gaming objects, etc. For example, for a gaming token, the value maybe $1, $10, $100, etc. As another example, for a gaming card, the valuemay be the two of hearts, the three of spades, etc.

The computer 110 uses the game rule database to control a game staterelated to the gaming table 120. For example, the game rules mayprohibit bets from being changed during a defined period; when thecomputer 110 detects the reflection coefficients for a selected antenna122 change during that defined period, the computer 110 may generate analert. As another example, the game rules may define a transition fromone state to another state when the dealer moves a gaming object into aparticular area; when the computer 110 detects the change in thereflection coefficients for the antenna 122 that corresponds to theparticular area, the computer 110 may change the game state.

In general, the network analyzer 106 takes between 0.25 and 0.45milliseconds to obtain the reflection coefficients for one of theantennas 122, and the RFID reader 108 takes between 5 and 10milliseconds to read the RFID tags near a particular antenna. For theRFID reader 108, the read time increases as the number of RFID tags inthe read area increases. But for the network analyzer 106, the time toobtain a set of reflection coefficients is mainly dependent upon thenumber of reflection coefficients in the set. As detailed further below,the system 100 uses these time differences to perform a high rate ofobtaining reflection coefficients with the network analyzer 106, todetect which sets of reflection coefficients change for one or moreparticular antennas 122, and then to read with the RFID reader 108 onlythose one or more particular antennas 122 that have the changed sets ofreflection coefficients. In this manner, read time savings can beachieved, since the system 100 does not have to read all of the antennas122.

In general, the control board 104 and the computer 110 may be referredto as a control device. The RFID reader 108 may also be considered partof the control device, for example when the computer 110 controls theRFID reader 108 to energize a selected antenna 122 or to perform a readof the selected antenna 122. Further details of the system 100 areprovided below.

FIGS. 2A-2E are polar diagrams showing examples of reflectioncoefficient measurements by the network analyzer 106 (see FIG. 1) forone of the antennas 122. The polar diagrams are also applicable to theother systems described herein. Each of the polar diagrams of FIGS.2A-2E shows the measurements made between 13.26 and 13.86 MHz. FIG. 2Ashows the measured reflection coefficients for zero RFID tags (line 200)and one RFID tag (line 201). FIG. 2B shows the measured reflectioncoefficients for zero RFID tags (line 200) and five RFID tags (line202). FIG. 2C shows the measured reflection coefficients for zero RFIDtags (line 200) and ten RFID tags (line 203). FIG. 2D shows the measuredreflection coefficients for zero RFID tags (line 200) and twenty RFIDtags (line 204). FIG. 2E shows the measured reflection coefficients forzero RFID tags (line 200) and thirty RFID tags (line 205).

The computer 110 may store these measurements in the databases 130(e.g., in the reflection coefficients database). The values stored maybe polar values (e.g., magnitude and phase or rho and theta, as shown inFIGS. 2A-2E), x and y values, I and Q (in-phase and quadrature) values,scattering parameters (S₁₁ or S₂₂, e.g. as plotted on a Smith chart),etc. The computer 110 need not store a large set of values thatcorrespond to one of the lines (e.g., the line 200). Instead, thecomputer 110 may store (for a particular antenna 122) a set of a fewvalues, such as four, six, eight, ten, twelve, etc. The set of valuesmay correspond to the baseline reflection coefficients, or to thepreviously measured reflection coefficients. The computer 110 may thendetect the change in the reflection coefficients by comparing thebaseline set and the currently measured set, or by comparing thepreviously measured set and the currently measured set. Alternatively,the computer 110 may store two sets of values (one set for the baselinereflection coefficients and another set for the previously measuredreflection coefficients). The computer 110 may then detect the change inthe reflection coefficients by comparing the currently measured set andeither the baseline set or the previously measured set.

As another alternative, the control board 104 and network analyzer 106(see FIG. 1) can detect the change in reflection coefficients. Thecontrol board 104 includes a memory that stores the baseline reflectioncoefficients for all the antennas 122 (see FIG. 1). When the networkanalyzer 106 obtains the currently measured reflection coefficients, thecontrol board 104 compares these to the baseline in order to determinewhich of the antennas 122 have gaming objects associated therewith. Thecontrol board 104 then provides these corresponding antennas 122 to thecomputer 110, and the computer 110 instructs the RFID reader 108 (seeFIG. 1) to read those corresponding antennas 122.

Further details on how the system 100 detects the changes are providedbelow.

FIG. 3 is a block diagram of a system 300 for detecting events in agaming environment. The system 300 is similar to the system 100 (seeFIG. 1), but having a combined RFID reader and network analyzer 308. Thesystem 300 also includes a seat board 302 with one or more antennas 322and an antenna selection circuit 326 (which are similar to the seatboard 102, antennas 122 and antenna selection circuit 126 of FIG. 1);and a computer 310 storing databases 330 (which are similar to thecomputer 110 and databases 130 of FIG. 1). The computer 310 communicatesantenna address information 325 to the seat board 302 (in a mannersimilar to the antenna address information 125 of FIG. 1).

The combined RFID reader and network analyzer 308 performs functionssimilar to those of the RFID reader 108 and network analyzer 106 ofFIG. 1. For example, the detection process may be performed as follows.The computer 310 selects one of the antennas 322 using the antennaaddress information 325, and instructs the combined RFID reader andnetwork analyzer 308 to perform its network analyzer function on theselected antenna 322. The combined RFID reader and network analyzer 308sends the reflection coefficients resulting from analyzing the selectedantenna 322 to the computer 310. The computer 310 compares the resultingreflection coefficients to the previous set of reflection coefficientsor the baseline set of reflection coefficients for the selected antenna322, for example by using the reflection coefficients database. When thecomputer 310 detects that the reflection coefficients have changed, thecomputer 310 instructs the combined RFID reader and network analyzer 308to perform its RFID reader function on the selected antenna 322, and thecombined RFID reader and network analyzer 308 sends the detected RFIDtag identifiers to the computer 310. When the computer 310 detects thatthe reflection coefficients have not changed, the computer 310 selectsanother one of the antennas 322 for the network analyzer function, andthe process repeats for that antenna; and so on.

FIG. 4 is a block diagram of a system 400 for detecting events in agaming environment. The system 400 is similar to the system 100 (seeFIG. 1), but with multiple seat boards 402 a-402 d (collectively 402).The seat boards 402 have antennas 422 a-422 d (collectively 422) andantenna selection circuits 426 a-426 d (collectively 426). The seatboards 402 are associated with multiple switches 424 a-424 d(collectively 424), multiple network analyzers (NA) 406 a-406 d(collectively 406), and multiple RFID readers 408 a-408 d (collectively408). The seat boards 402 are associated with a control board 404. Aswith the multiple antennas 122 (see FIG. 1), one of the collectivecomponents may be referred to by number as the selected component, theparticular component, or the corresponding component (e.g., “thecorresponding switch 424” refers to a corresponding one of the switches424). The seat boards 402, switches 424, RFID readers 408, and controlboard 404 (with the network analyzers 406) may be components of a gamingtable 420 (similar to the gaming table 120 of FIG. 1). A computer 410(similar to the computer 110 of FIG. 1), with databases 430 (similar tothe databases 130 of FIG. 1), connects to the RFID readers 408 and thecontrol board 404.

The number of seat boards 402 may be increased or decreased as desired.In general, each seat board 402 corresponds to one player position atthe gaming table 420. The number, shape and size of the antennas 422 maybe adjusted as desired. In general, each antenna 422 corresponds to anarea in which gaming objects are read, such as a betting spot for gamingtokens. The antennas 422 may also include geofencing antennas, forexample one geofence antenna per seat board 402.

The system 400 performs the detection process in a manner similar tothat of the system 100 (see FIG. 1). The computer 410 selects one of theantennas 422 and sends the antenna address information 425 to thecontrol board 404. The control board 404 determines which seat board402, switch 424 and network analyzer 406 correspond to the selectedantenna 422. The control board 404 uses the switch control information423 to control the corresponding switch 424 to connect the correspondingnetwork analyzer 406 to the corresponding seat board 402. The controlboard 404 sends the antenna address information 425 to the correspondingantenna selection circuit 426 of the corresponding seat board 402. Thecorresponding antenna selection circuit 426 receives the radio frequencyscan from the corresponding network analyzer 406 and routes it to theselected antenna 422. The selected network analyzer 406 determines thereflection coefficients that result from scanning the selected antenna422 with radio frequency (RF) energy and sends the reflectioncoefficients to the computer 410. The computer 410 determines whetherthe reflection coefficients have changed for the selected antenna 422.If the reflection coefficients have not changed, the computer 410selects another antenna 422 and repeats the process of detecting thereflection coefficients for the new selected antenna 422.

When the computer 410 determines that the reflection coefficients havechanged for the selected antenna 422, the computer 410 instructs thecontrol board 404 to change the corresponding switch 424 to connect thecorresponding RFID reader 408 to the selected antenna 422. The computer410 instructs the corresponding RFID reader 408 to perform a read of theselected antenna 422 using RF energy. The corresponding RFID reader 408sends the RFID identifiers resulting from the read to the computer 410.The computer then selects another antenna 422 and repeats the process ofdetecting the reflection coefficients.

FIG. 5 is a block diagram of a system 500 for detecting events in agaming environment. The system 500 is similar to the system 300 (seeFIG. 3), but with multiple seat boards 502 a-502 d (collectively 502).The seat boards 502 have antennas 522 a-522 d (collectively 522) andantenna selection circuits 526 a-526 d (collectively 526). The seatboards 502 are associated with multiple combined RFID readers andnetwork analyzers 508 a-508 d (collectively 508), which are similar tothe combined RFID reader and network analyzer 308 (see FIG. 3). The seatboards 502 and the combined RFID readers and network analyzers 508 maybe components of a gaming table 520 (similar to the gaming table 320 ofFIG. 3). A computer 510 (similar to the computer 310 of FIG. 3), withdatabases 530 (similar to the databases 330 of FIG. 3), connects to thecombined RFID readers and network analyzers 508, and communicatesantenna address information 525 to the seat boards 502 (in a mannersimilar to the antenna address information 325 of FIG. 3).

In general, the computer 510 controls each combined RFID reader andnetwork analyzer 508 independently. Thus, some of the combined RFIDreaders and network analyzers 508 may be performing their networkanalyzer functions, at the same time others of the combined RFID readersand network analyzers 508 may be performing their RFID reader functions.

FIG. 6 is a block diagram of a seat board 600. The seat board 600 may besimilar to the seat board 102 (see FIG. 1), the seat board 302 (see FIG.3), etc. The seat board 600 may be one of a number of seat boards (e.g.,one of the seat boards 402 of FIG. 4) on a gaming table (e.g., 420 inFIG. 4), as part of a gaming system (e.g., the system 400 of FIG. 4, 500of FIG. 5, etc.). The seat board 600 includes antennas 622 and anantenna selection circuit 626 (similar to the antenna selection circuit126 of FIG. 1, 326 of FIG. 3, etc.). The antenna selection circuit 626receives the antenna address information 625 (e.g., from a control boardsuch as 104 in FIG. 1 or a computer such as 310 in FIG. 3), and routesradio frequency (RF) energy (e.g., from a network analyzer such as 106in FIG. 1 or an RFID reader such as 108 in FIG. 1) to and from theselected antenna 622. (To avoid cluttering the figure, the connectionsfrom the antenna selection circuit 626 to each of the antennas 622 arenot shown.) The antennas 622 include spot antennas 640, a stash antenna642, and a geofence antenna 644. The seat board 600 may be oriented onthe gaming table such that the stash antenna 642 is close to a player(or other customer) and the geofence antenna 644 is close to a dealer(or other employee).

The spot antennas 640 generally correspond to betting spots, so thenumber, size and placement of the spot antennas 640 may be adjusted asdesired to conform to the betting spots. In addition, some of the spotantennas 640 may have no corresponding betting spots, in which case thesystem need not energize them. The operation of the spot antennas 640generally corresponds to the operation of the antennas described above(e.g., the antennas 122 of FIG. 1, 322 of FIG. 3, etc.). An embodimenthas 36 circular spot antennas, approximately 1 inch in diameter, in a6×6 array.

The stash antenna 642 generally corresponds to a stash area in which aplayer places gaming tokens that are not currently in play. Reading theidentifiers of gaming objects placed in the stash area allows the systemto determine which gaming objects are associated with that player and totrack the player as he or she moves from table to table. For this playertracking function, it is only necessary for the system to read a subsetof the chips in the stash area. For example, as a player sits at a firsttable, the system reads all of the player's chips in the stash area ofthe first table. When the player moves to a second table, the systemjust needs to read one chip in the stash area of the second table toidentify it as one of the group of chips that was previously associatedwith the player at the first table.

The system may coordinate reading of the spot antennas 640 and the stashantenna 642 according to the game state information. For example, duringthe gameplay states (e.g., the bets allowed state, etc.) the systemreads the spot antennas 640 but not the stash antenna 642, since theimportant information is the gaming objects being placed and movedaround on the spot antennas 640. But between games, the system reads thestash antenna 642 but not the spot antennas 640, since the movement ofgaming objects around the spot antennas 640 is not important betweengames.

The geofence antenna 644 generally corresponds to an area in which thedealer may move a gaming object in order to change a game state. Thegaming object may be a wristband, in which case the geofence antenna 644may be used to detect the movement of the dealer's hand. The wristbandincludes a resonant circuit, such as a inductor-capacitor (LC) circuitor an RFID tag. If the wristband has the LC circuit and not the RFIDtag, the geofence antenna 644 need not be connected to an RFID reader.An example of how the geofence antenna 644 may be used for blackjack isas follows. Each player at the blackjack table has a corresponding seatboard 600 with a corresponding geofence antenna 644. When the dealerdeals a card to the player, the dealer's wristband crosses over thecorresponding geofence antenna 644. Thus, the system detects that thecard was dealt to that particular player according to the change inreflectance of the geofence antenna 644.

The system may coordinate reading the geofence antenna 644 according tothe game state information. For example, during the “winning betsremoved” state, the procedure is for the player to move their winningchips from the betting spots to the stash. If the dealer incorrectlymoves the wristband across the geofence antenna 644 to pick up thewinning chips, the system is able to generate an alert resulting fromdetecting the changed reflectance of the geofence antenna 644. Asanother example, during the “losing bets removed” state, the procedureis for the dealer to remove the losing chips from the betting spots. Thesystem is able to generate an alert if the system does not detect(within a defined time period) the dealer's wristband moving over thegeofence antenna 644 to pick up the losing chips.

Since the network analyzer function is faster than the RFID function,the spot antennas 640 may be read faster than if they were read usingonly the RFID function. For example, assume that the RFID reader takes 5milliseconds to perform a read of one of the 27 spot antennas 640, andthat the gaming objects are within one of the spot antennas 640 (e.g.,one stack of gaming objects). Thus, using the RFID reader alone to readthe gaming objects and to determine their location within the spotantennas 640 takes 135 milliseconds, since it needs to read all 27 ofthe antennas 640. Further assume that the network analyzer takes 0.35milliseconds to obtain the reflection coefficients of one of the spotantennas 640. Thus, using both the network analyzer and the RFID readerto read the gaming objects and to determine their location within thespot antennas 640 takes 14.45 milliseconds: 9.45 milliseconds to obtainthe reflection coefficients of 27 of the spot antennas 640, and 5milliseconds to read the particular antenna 640. Similarly, if thegaming objects are located within two of the spot antennas 640 (e.g.,two stacks of gaming objects), using both the network analyzer and theRFID reader to read the gaming objects and to determine their locationstakes 19.45 milliseconds.

As another example, assume instead 36 spot antennas 640 in addition tothe stash antenna 642 and the geofence antenna 644, and assume that theRFID reader takes 5 milliseconds to perform a read of one of theantennas 622. Thus, using the RFID reader alone to read the gamingobjects and to determine their location on the antenna array takes 190milliseconds, since it needs to read all 38 of the antennas 622. Furtherassume that the network analyzer takes 0.35 milliseconds to obtain thereflection coefficients of one of the antennas 622. Thus, it takes 13.3milliseconds to for the network analyzer to scan all 38 antennas. TheRFID reader is then directed to read the antennas that have been foundto have gaming objects on them by the network analyzer. If 10 antennashave a chip on them it will take the RFID reader 50 milliseconds to readthose tags.

FIG. 7 is a block diagram of a seat board 700. The seat board 700 may besimilar to the seat board 600 (see FIG. 6) and may be one of a number ofseat boards (not shown) on a gaming table (not shown), as part of agaming system (e.g., the system 100 of FIG. 1, 300 of FIG. 3, etc.). Theseat board 700 includes antennas 722 and an antenna selection circuit726 (similar to the antenna selection circuit 626 of FIG. 6). (To avoidcluttering the figure, the connections from the antenna selectioncircuit 726 to each of the antennas 722 are not shown.) The antennas 722include horizontal antennas 750 a-750 d (collectively 750) and verticalantennas 752 a-752 d (collectively 752). (Note that the terms horizontaland vertical are used in order to be descriptive of what is shown inFIG. 7, but it is to be understood that both sets of antennas aregenerally planar with respect to the gaming table.) The seat board 700may also include a stash antenna (not shown), a geofencing antenna (notshown), or other antennas (not shown).

The horizontal antennas 750 overlap each other, and the verticalantennas 752 overlap each other. The antennas that are overlapped areshown with dotted lines. The horizontal antennas 750 intersect with thevertical antennas 752. The horizontal antennas 750 and the verticalantennas 752 together may be referred to as overlapping, intersectingantennas, or as an antenna array. The antennas are overlapping to reducethe possibility of dead spots between antennas. The location of a gamingobject corresponds to the intersection of one of the horizontal antennas750 and one of the vertical antennas 752. In general, each intersectionarea corresponds to a betting spot on the gaming table.

The antenna selection circuit 726 receives the antenna addressinformation 725, and routes radio frequency energy (e.g., from a networkanalyzer such as 106 in FIG. 1 or an RFID reader such as 108 in FIG. 1)to and from the selected antenna 722. The general process of detectingand locating gaming objects is as follows.

First, the antenna selection circuit 726 routes radio frequency energyfrom the network analyzer selectively to the antennas oriented in onedirection (e.g., the horizontal antennas 750), and selectively to theantennas oriented in the other direction (e.g., the vertical antennas752). For example, the antenna address information 725 may instruct theantenna selection circuit 726 to cycle 750 a, 750 c, 750 b, 750 d, 752a, 752 c, 752 b, 752 d. The network analyzer sends the resultingreflection coefficients to the system. When the system detects a changein the reflection coefficients for one of the horizontal antennas 750and one of the vertical antennas 752, this indicates a change in thegaming objects located at the intersection of those two antennas.

Second, the antenna selection circuit 726 routes radio frequency energyfrom the RFID reader selectively to the particular horizontal antenna750 and the particular vertical antenna 752 that were identifiedaccording to the changed reflection coefficients. The RFID reader sendsthe resulting tag identifiers to the system, and the system associatesthose tags with the betting spot corresponding to the intersection ofthe particular horizontal antenna 750 and the particular verticalantenna 752.

In a similar manner, the system may detect changes in the reflectioncoefficients at multiple intersection areas. For example, the networkanalyzer detects reflectance changes on the vertical antenna 752 a, andon two horizontal antennas 750 a and 750 d. The system then controls theRFID reader to read those three identified antennas, and associates thetwo groups of tags read with the two corresponding betting spots.

The antenna groups 750 and 752 may intersect at various angles. Forexample, FIG. 7 shows a configuration in which the horizontal antennas750 and the vertical antenna 752 intersect at right angles. As anotherexample, the horizontal antennas 750 and the vertical antenna 752 mayintersect at 45 degrees. The antennas 722 may differ in quantity, sizeand shape. For example, when the area covered by the antenna arrayincludes large betting spots and small betting spots, the antennas 722under the large spots may be larger than the antennas 722 under thesmall spots. The antenna array shown in FIG. 7 may otherwise be similarto the overlapping, intersecting antennas disclosed in U.S. ApplicationPub. No. 2015/0141126, which is incorporated herein by reference.

FIG. 8 is a block diagram of a network analyzer 800 and relatedcomponents (an antenna 822 and a switch 824). The network analyzer 800is similar to, and may show more details for, the network analyzer 106of FIG. 1, 406 of FIG. 4, the network analyzer component of the combinedRFID reader and network analyzer 308 of FIG. 3, etc. The antenna 822 issimilar to the antennas 122 (see FIG. 1), but omitting some details suchas the connections via the antenna selection circuit 126 (see FIG. 1).The switch 824 is similar to the switch 124 (see FIG. 1), selectivelyconnecting one of the network analyzer 800 and an RFID reader (e.g., theRFID reader 108 of FIG. 1) to the antenna 822, as controlled by a signalfrom a control board (e.g., the control board 104 of FIG. 1). Thenetwork analyzer 800 includes a processor 860, an oscillator 862, adirectional coupler 864, mixers 866 a and 866 b, a phase shifter 868,low pass filters (LPF) 870 a and 870 b, and analog to digital (A/D)converters 872 a and 872 b. In general, the network analyzer 800implements an I/Q (in phase and quadrature) receiver.

The processor 860 generally controls the operation of the networkanalyzer 800. The processor 860 controls the oscillator 862, receivesinformation from the analog to digital converters 872 a and 872 b, andcommunicates with a computer (e.g., the computer 110 of FIG. 1, thecomputer 310 of FIG. 3, etc.). For example, the computer may instructthe network analyzer 800 to measure the reflectance of the antenna at agiven frequency.

The oscillator 862 generally generates a radio frequency signal at thefrequency instructed by the processor 860. For example, for gamingobjects that operate at 13.56 MHz, the oscillator 862 may generallyoperate between 12 and 14 MHz. As another example, if there is onegaming object near the antenna 822, and the processor 860 instructs theoscillator 862 to step from 13.26 MHz to 13.86 MHz in 0.003 MHzincrements (200 frequencies), the resulting reflection coefficients haverho and theta values that correspond to the line 201 in FIG. 2A. Theoscillator 862 provides its output to the directional coupler 864 and tothe mixers 866 a and 866 b.

The directional coupler 864 generally couples the output from theoscillator 862 to the antenna 822 and to the mixers 866 a and 866 b(line 865). The signal 865 coupled back to the mixers 866 a and 866 b isless in power than that coupled to the antenna 822, e.g. −10 dB. Unlessthere is a perfect match to the antenna 822, some amount of the signalgoing to the antenna 822 is reflected back. The directional coupler 864picks off a fraction of the reflected signal and sends it to the mixers866 a and 866 b. The radio frequency signal from the oscillator 862 thatis coupled to the antenna 822 has a reflectance that corresponds to thereflection coefficients. As gaming objects couple with and uncouple fromthe antenna 822, the reflection coefficients at the selected frequencyfrom the oscillator 862 change. The reflectance is then a component ofthe signal 865 coupled back to the mixers 866 a and 866 b.

The mixer 866 a, the low pass filter 870 a, and the analog to digitalconverter 872 a generally implement an in phase (I) path for the signal865 reflected back from the antenna 822. The mixer 866 a receives thesignal 865 from the directional coupler 864 and demodulates the signal865 with the output of the oscillator 862, generating an in phase (I)component of the reflectance. The low pass filter 870 a performs lowpass filtering on the in phase (I) component, then the analog to digitalconverter 872 a converts the filtered in phase (I) component into adigital signal that is provided to the processor 860.

The phase shifter 868 generally shifts the phase of the output of theoscillator 862 by 90 degrees and provides the phase shifted signal tothe mixer 866 b.

The mixer 866 b, the low pass filter 870 b, and the analog to digitalconverter 872 b generally implement a quadrature (Q) path for the signal865 reflected back from the antenna 822. The mixer 866 b receives thesignal 865 from the directional coupler 864 and demodulates the signal865 with the output of the phase shifter 868 (the phase shifted outputof the oscillator 862), generating a quadrature (Q) component of thereflectance. The low pass filter 870 b performs low pass filtering onthe quadrature (Q) component, then the analog to digital converter 872 bconverts the filtered quadrature (Q) component into a digital signalthat is provided to the processor 860.

The processor 860 receives the digital I and Q components from theanalog to digital converters 872 a and 872 b, and provides them to thecomputer (e.g., the computer 110 of FIG. 1).

FIG. 9 is a block diagram of a network analyzer 900 and relatedcomponents (an antenna 922 and a switch 924). The network analyzer 900is similar to, and may show more details for, the network analyzer 106of FIG. 1, 406 of FIG. 4, the network analyzer component of the combinedRFID reader and network analyzer 308 of FIG. 3, etc. The antenna 922 issimilar to the antennas 122 (see FIG. 1), but omitting some details suchas the connections via the antenna selection circuit 126 (see FIG. 1).The switch 924 is similar to the switch 124 (see FIG. 1), selectivelyconnecting one of the network analyzer 900 and an RFID reader (e.g., theRFID reader 108 of FIG. 1) to the antenna 922, as controlled by a signalfrom a control board (e.g., the control board 104 of FIG. 1). Thenetwork analyzer 900 includes a processor 960, an oscillator 962, adivider 974, a low pass filter 970, a directional coupler 964, an analogto digital converter 972, and a latch 976. In general, the networkanalyzer 900 implements an I/Q (in phase and quadrature) receiver.

The processor 960 generally controls the operation of the networkanalyzer 900. The processor 960 controls the oscillator 962, receivesinformation from the latch 976, and communicates with a computer (e.g.,the computer 110 of FIG. 1, the computer 310 of FIG. 3, etc.). Forexample, the computer may instruct the network analyzer 900 to measurethe reflectance of the antenna at a given frequency.

The oscillator 962 generally generates a radio frequency signal at thefrequency instructed by the processor 960. The oscillator 962 operatesin combination with the divider 974 to generate frequencies that areappropriate for the gaming objects. For example, for gaming objects thatoperate at 13.56 MHz, the divider 974 divides by four and the oscillator962 may generally operate between 48 and 56 MHz (so that the resultingrange is 12 to 14 MHz). As another example, if there is one gamingobject near the antenna 922, and the processor 960 instructs theoscillator 962 to step from 53.04 MHz to 55.44 MHz in 0.012 MHzincrements (200 frequencies), the resulting reflection coefficients haverho and theta values that correspond to the line 201 in FIG. 2A. Theoscillator 962 provides its output to the divider 974 and to the latch976 (as the clock signal 963).

The divider 974 generally divides the output from the oscillator 962 byfour to return the frequency to the desired operational range for thegaming objects (e.g., from 53.04-55.44 MHz to 13.26-13.86 MHz). Thedivider 974 provides the divided frequency signal to the low pass filter970.

The low pass filter 970 generally performs low pass filtering on thedivided frequency signal to eliminate any harmonics. The low pass filter970 provides the filtered signal to the directional coupler 964.

The directional coupler 964 generally couples the filtered signal fromthe low pass filter 970 to the antenna 922 and to the analog to digitalconverter 972 (line 965). The signal 965 coupled back to the analog todigital converter 972 is less in power than that coupled to the antenna922, e.g. −10 dB. Unless there is a perfect match to the antenna 922,some amount of the signal going to the antenna 922 is reflected back.The directional coupler 964 picks off a fraction of the reflected signaland sends it to the analog to digital converter 972. The radio frequencysignal from the oscillator 962 and the divider 974 that is coupled tothe antenna 922 has a reflectance that corresponds to the reflectioncoefficients. As gaming objects couple with and uncouple from theantenna 922, the reflection coefficients at the selected frequency fromthe oscillator 962 change. The reflectance is then a component of thesignal 965 coupled back to the analog to digital converter 972.

The latch 976, since it is clocked by the undivided output 963 from theoscillator 962, operates at four times the frequency of the signalcoupled to the antenna 922 (and reflected back as the signal 965). Theclock signal 963 operates as a 4× sampling clock that is synchronouswith the signal sent to the antenna 922. This enables the latch 976 todetect the I and Q channels of the signal 965 by sampling the signal 965at four times the frequency. The latch 976 sends the I and Q channels tothe processor 960.

The processor 960 combines the I and Q channel data from the latch 976to determine the I and Q components of the reflected signal 965, andprovides them to the computer (e.g., the computer 110 of FIG. 1). Theprocessor may determine the I and Q components as follows. If thefrequency we wish to measure is 13 MHz, then the sampling rate is 52 MHzon the analog to digital converter 972. For example, if the samples aresequentially numbered 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, . . . ,then the I value is obtained by the sum of sample 1−sample 3+sample5−sample 7+sample 9−sample 11, etc. This sum is then divided by thenumber of samples to normalize it. The Q value is the sum of sample2−sample 4+sample 6−sample 8+sample 10−sample 12, etc. Again divided bythe number of samples to normalize it. The processor 960 may be acomponent of a field programmable gate array (FPGA) circuit thatperforms the combination.

FIG. 10 is a flowchart of a method 1000 of detecting events in a gamingenvironment. The method 1000 may be performed by the system 100 (seeFIG. 1), 300 (see FIG. 3), etc. For example, the computer 110 (seeFIG. 1) may execute a computer program that controls the components ofthe system 100 to perform the method 1000.

At 1002, a plurality of reflection coefficients that are associated witha plurality of antennas positioned on a gaming table are selectivelydetected. For example, the network analyzer 106 (see FIG. 1) mayselectively detect the reflection coefficients associated with theantennas 122 on the gaming table 120, as controlled by the computer 110and the control board 104. The reflection coefficients change as aplurality of RFID tags interact with the plurality of antennas. Forexample, gaming objects that include the RFID tags may couple with ordecouple from the antennas 122, which change the reflectioncoefficients.

At 1004, a subset of the plurality of antennas are selectively energizedaccording to the change in the plurality of reflection coefficients. Forexample, the RFID reader 108 (see FIG. 1) may selectively energize thesubset of antennas that have the changed reflection coefficients (see1002).

At 1006, a subset of the plurality of RFID tags is read when the subsetof the plurality of antennas is energized. For example, the RFID reader108 (see FIG. 1) may read the RFID tags in the gaming objects that areassociated with the subset of antennas that have the changed reflectioncoefficients (see 1002). The flow may then return to 1002.

At 1008, a game state related to the gaming table in the gamingenvironment is controlled in response to the change in the plurality ofreflection coefficients. For example, when the dealer moves a gamingobject across the geofence antenna 644 (see FIG. 6), the computer 110(see FIG. 1) changes a game state related to the gaming table 120. Theflow may then return to 1002.

As can be seen from the flow, detecting the reflection coefficients (see1002) can be used for two purposes: to determine which antennas toenergize for a read operation (see 1004 and 1006), or to control thegame state (see 1008).

The following sections provide more details regarding the systems andmethods described above.

Additional Details

As mentioned above, embodiments are directed to improving the speed ofdetecting gaming objects in a gaming environment. Example gaming objectsinclude betting tokens (or gaming chips), gaming cards, and a dealer'swristband (or other object associated with the hand or wrist of a dealeror other employee).

Regarding betting tokens, the system is able to accurately locate gamingchips on the gaming table using RFID antennas (e.g., the antennas 122 ofFIG. 1). The system is able to reduce the time involved in scanning andreading all the antennas by first detecting changes in reflectioncoefficients with a network analyzer (e.g., the network analyzer 106 ofFIG. 1), then by only reading those antennas associated with the changedreflection coefficients.

Regarding gaming cards, identifying and tracking the distribution ofcards in real-time on a gaming table can augment the information fromtracking betting tokens. Identifying the suit and face value of eachcard and knowing where each card was dealt can define winners andlosers. In some games (e.g. Blackjack), the distribution of cards isunpredictable (a player can choose to “hit” or not) and the system isable to determine where the card went in order to determine winners andlosers. The system detects the placement of a card by identifying thenearest antenna, and determines the suit and value of the card byreading an RFID tag in the card.

Regarding a dealer's wristband, the system detects changes in thereflection coefficients of a geofence antenna (e.g., the geofenceantenna 644 of FIG. 6) when the dealer moves his or her hand (with thewristband or other gaming object) over the geofence antenna. Each gameon a gaming table has rules that track proper behavior on the part ofdealers and players. But the appropriate set of rules evolves throughdifferent phases of a game. For example, there is a point at whichplayers are no longer allowed to change their bets (typically prior todealing the cards), and another point at which the game outcome is known(typically when a dealer turns his cards face up). One can think of eachof these as defining a change in the “game state”. The system is able todetect when the dealer deals the cards, by detecting the dealer'swristband coupling with the geofence antenna as the dealer moves hishand to deal the card to the player. The system is able to detect whenthe game is over, by detecting the dealer's wristband coupling with thegeofence antenna as the dealer moves his hand. For example, once theoutcome of the game is known (e.g., the dealer has shown his hand), theprocedure is to resolve winning and losing bets seat by seat (e.g.,clockwise). The system reads the geofence antenna to detect the presenceof the wristband when a particular seat is being resolved. When the lastseat has been resolved, the system transitions to the next game state(e.g., game over state, new game state, etc.).

The system may implement a game rule database (e.g. using the databases130 of FIG. 1) that the system applies as the system detects the gamemoving from one game state to another. For example, a “bet” refers to agroup of RFID tags that are read in a betting spot. The game rulesdefine actions that are allowed, or disallowed, for the bet according tothe game state. One example is detecting a change in location of thebet: Bets are not allowed to be moved from one betting spot to anotherin some game states (e.g., after the “bets locked” event). Anotherexample is detecting a change in value of the bet: Additional RFID tagsare not allowed to be added to or removed from the bet in some gamestates (e.g., after the “bets locked” event). Another example isdetecting a late placement of the bet: Additional bets are not allowedto be made in some game states (e.g., after the “bets locked” event).Another example is detecting an improper removal of the bet in a losingsituation: The system generates an alert if it fails to detect thedealer wristband moving over the geofence antenna to collect the losingbet within a defined time period during the “remove losing bets” gamestate. Another example is detecting an improper payout to the bet in awinning situation: The system reads the RFID tags in the betting spotafter the dealer has paid out the winning bet, and generates an alert ifthe payout amount is incorrect. Detecting the game state, generatingalerts, etc. may otherwise be as described in U.S. Application Pub. No2015/0312517, which is incorporated herein by reference.

Network Analyzer Details

Traditionally, a network analyzer is used to measure and optimize theimpedance matching of a RFID reader, an antenna, and one or more RFIDtags. In contrast, embodiments described herein measure and exploitchanges in the reflection coefficient to regularly check on the presence(or absence) of objects entering (or leaving) the excitation field ofthe RFID reader. The systems described herein integrate network analyzerfunctionality (the ability to measure reflection coefficient) with theRFID reader, and detect any de-tuning of the reader antenna's resonantcircuit. The resulting shift in reflection coefficient is greater whenthe object in the field is resonant within the frequency response of theexcitation antenna. Thus the reflection coefficient can be a sensitiveand selective detector of proximal resonant circuits.

One feature enabled by using the network analyzer is to increase theread speed of the gaming table. Since reading of tags can be timeconsuming (e.g., it can take 20 milliseconds to identify each tag),there is value in being able to know—a priori of taking areading—whether or not there is a tag in the field. This issue isexacerbated when one needs to read a large number of antennas quickly.Even more of a problem is when the system is using these antennas tohelp define the location of one or more tags and there is “crosstalk”between neighboring antennas. In addition, there is an associatedoverhead even when no tags are in the field (e.g., it can takes 10milliseconds to determine there are no tags in the vicinity). Knowingwhich antennas actually have tokens on them and which do not can greatlyspeed up the time it takes for the RFID reader to identify the tags anddetermine their proper location.

The system uses a circuit to determine the antenna reflectioncoefficient over a range of one or more frequencies to determine ifthese reflection coefficients are different from an establishedbaseline. This measurement (using the network analyzer) can be doneacross a number of antennas at a rate that is significantly faster thanit takes to energize and read an RFID tag (using the RFID reader). Theresults of this measurement can then be used to direct the RFID scan tospecific antennas. In one embodiment, it takes 300 microseconds to scana single antenna at three different frequencies. In one embodiment, thethree frequencies are 12.8, 13.2, and 13.6 MHz.

Another feature enabled by using the network analyzer is geofencing. Theintegration of a network analyzer with the system can be used to createa geofence (see FIG. 6) to determine the presence of any properly tunedcircuit very quickly. This allows the detection of highly transitoryevents. The network analyzer has a very fast measurement cycle—muchfaster than that of an RFID reader alone. In one embodiment, the systemdetects tuned circuits built into laminated cards. The same tunedcircuit can used for all cards (e.g., the cards do not each have adistinct identifier). An instrumented shoe may be used to determine theface value of each card and the geofence antenna may be used todetermine where that card was dealt. Knowing which cards were dealt andto whom they were dealt is valuable information. In another embodiment,tuned circuits are built into wristbands worn by the dealer. Thegeofence antenna is used to detect when the dealer's hands have crossedover to manipulate tokens (e.g. collect losing bets or payout winningbets). This information can be valuable when defining automated rulesfor proper game play.

Determining Reference Reflectances

The reference (also referred to as baseline) reflectances for eachantenna may be initially determined when the gaming table (e.g., 120 inFIG. 1, etc.) is installed. The system may store the baselinereflectance information in a database (e.g., the reflection coefficientsdatabase in the databases 130 of FIG. 1), in a memory of the controlboard (e.g., 104 in FIG. 1), etc. The process for obtaining the baselinereflectances is as follows. First (1), the system uses the RFID reader(e.g., 108 in FIG. 1) to read an antenna, in order to determine that nogaming objects are coupled to the antenna. Second (2), the system usesthe network analyzer (e.g., 106 in FIG. 1) to obtain the reflectioncoefficient at a first frequency. Third (3), the system uses the RFIDreader (e.g., 108 in FIG. 1) to read the antenna again; if the RFIDreader detects gaming objects, then the reflection coefficient isdiscarded. Fourth (4), the system performs the steps (1)-(3) again fivemore times, to result in six measurements for the baseline reflectioncoefficients. Fifth (5), the system averages those six measurements touse as the baseline reflection coefficient for the first frequency.Sixth (6), the system performs the steps (1)-(5) for a second frequency.Seventh (7), the system performs the steps (1)-(5) for a thirdfrequency. Eighth (8), the system stores this set of three reflectioncoefficients as the baseline for that antenna, and the system moves onto determine the baseline for another antenna.

A similar process may be used once the system has been installed. Thereflectance of an antenna may change over time, for example due totemperature, humidity, etc. The system may perform this process in thebackground so that it does not degrade the performance of the system.For example, for a seat board with 36 antennas, one antenna issequentially selected as the network analyzer is scanning the seatboard; if no RFID tags are present to interrupt the cycle, the baselinevalues may all be updated after (36*6) 216 network analyzer scans. Theupdate process is similar to that described above. The system performsthe steps (1)-(4) as above. In place of the fifth (5) step, the systemdiscards the two measurements that are furthest away from the currentbaseline, and averages the remaining four measurements. Finally, thesystem performs the remainder of the steps (6)-(8) as above.

Matching Reflection Coefficients

As discussed above, the system (e.g., 100 in FIG. 1) need not measure orstore a large number of reflection coefficients over a particularfrequency range. Instead, the system may store a small set of reflectioncoefficients corresponding to a small number of reflectance measurementsin the particular frequency range. In one embodiment, the networkanalyzer (e.g., 106 in FIG. 1) measures the reflectance of a selectedantenna at three frequencies: 13.2, 13.3 and 13.4 MHz. Each frequencyhas corresponding rho and theta values, so the measurement for aparticular antenna results in six values. The system then compares themeasured six values with a stored set of six values (e.g., a baselineset corresponding to zero gaming objects, a previous set correspondingto the previous measurement for that antenna, etc.).

The threshold for determining if the difference between two detectedsets of reflection coefficients is significant enough to be classifiedas a “change” may be set as follows. First, the reflectance for theantenna at a particular frequency for zero gaming objects is measuredover one minute; the maximum of this measurement is the noise distance.Second, one gaming object is placed within the betting spot for theantenna and the reflectance is measured; this provides the single chipdistance. Third, the threshold may be set at a distance that is halfwaybetween the maximum noise distance and the single chip distance.

Other frequencies, and other numbers of frequencies, may be used asdesired according to the specifics of the implementation. Thesespecifics include the particular resonant frequency of the gamingobjects, the particular antenna size, the particular antenna shape, theparticular antenna reflectance, etc. For example, one frequency (withone set of values) may be used, two frequencies (with two sets ofvalues) may be used, four frequencies (with four sets of values) may beused, five frequencies (with five sets of values) may be used, etc. Asanother example, the frequencies of 13.2, 13.3 and 13.4 MHz may beadjusted upward or downward by between 0 and 0.05 MHz.

Antenna Cycling Options

As discussed above, the system (e.g., 100 in FIG. 1) first uses thenetwork analyzer (e.g., 106 in FIG. 1) to determine which of theantennas (e.g., 122 in FIG. 1) have a change in gaming objectsassociated therewith, then the system uses the RFID reader (e.g., 108 inFIG. 1) to read only those antennas with the change. There are a numberof ways the system can sequence the operation of the network analyzerand the RFID reader, depending upon the number of antennas, the numberof network analyzers, and the number of RFID readers.

Consider the system 100 of FIG. 1. One option is that the system 100 mayuse the network analyzer 106 to cycle through all of the antennas 122,then the system 100 may use the RFID reader 108 to read only thoseantennas 122 having the changed reflection coefficient. Another optionis that the system 100 may use the network analyzer 106 to cycle throughthe antennas 122; if a changed reflection coefficient is detected, thesystem 100 stops the network analyzer 106 at its current spot in thecycle and controls the RFID reader 108 to read that particular antenna122 having the changed reflection coefficient; after the particularantenna 122 has been read, the system 100 controls the network analyzer106 to continue on from its current spot in the cycle.

Consider the system 400 of FIG. 4. One option is that the system 400 maycontrol the network analyzers 406 and the RFID readers independently.For example, the system 400 may instruct each of the network analyzers406 independently to cycle through all of the antennas 422 on itscorresponding seat board 402, then the system 400 may independently useonly those RFID readers 408 associated with the seat boards 402 havingthe changed reflection coefficients to read the corresponding antennas422 having the changed reflection coefficients. The network analyzers406 and the RFID readers 408 may be controlled independently in thatwhen one network analyzer (e.g., 406 a) is measuring the reflectioncoefficients on its associated seat board (e.g., 402 a), the RFID reader(e.g., 408 b) associated with another seat board (e.g., 402 b) may beperforming RFID read operations.

As a variation for the system 400 of FIG. 4, the system 400 may instructa particular network analyzer 406 to stop cycling through the antennas422 on its corresponding seat board 402 when the system 400 detects achanged reflectance for a particular antenna 422. The system 400 thencontrols the corresponding RFID reader 408 to read that particularantenna 422. Once the corresponding RFID reader 408 has obtained theRFID tag identifiers, the system 400 instructs the particular networkanalyzer 406 to continue its scan.

Consider the seat board 600 of FIG. 6. One option is that the system(e.g., 100 in FIG. 1) instructs the network analyzer (e.g., 106 inFIG. 1) to scan the stash antenna 642 and the geofence antenna 644 eachtime the network analyzer scans one of the antennas 640 as it cyclesthrough the antennas 640. If the system detects a change in thereflectance of the geofence antenna 644, the system uses thatinformation to adjust the game state as discussed above. If the systemdetects a change in the reflectance of the stash antenna 642 or one ofthe antennas 640, the system controls the RFID reader (e.g., 108 inFIG. 1) to read the antenna with the changed reflectance. As anotheroption, the system cycles through all of the antennas 622 with thenetwork analyzer; then when the cycle is complete, the system uses theRFID reader to perform a read of those antennas having changedreflectances.

Geofence Features

As discussed above, the geofence antenna (e.g., 644 in FIG. 6) may beconnected to the network analyzer (e.g., 106 in FIG. 1) but not the RFIDreader (e.g., 108 in FIG. 1). In such an implementation, the gamingobjects that interact with the geofence antenna need not include an RFIDtag, but may only include another object that couples to the geofenceantenna and changes the reflection coefficients. The coupling may occuras the gaming object crosses over the geofence antenna, lands within oron top of the geofence antenna, etc. This other object may be ametalized layer in a gaming card, a resonant circuit (e.g., an LCcircuit) in a dealer wristband, etc.

Regarding gaming cards, one way for the system to determine the value(e.g., rank and suit) of a gaming card is to use an instrumented gamingshoe that reads a gaming card as the dealer removes it from theinstrumented shoe, or to use a camera that captures an image of thegaming card for the system to identify using pattern recognition. Incombination with the geofence antenna, the system may then determine towhich player seat a particular gaming card is dealt, by monitoring thegeofence antennas of the seat boards (e.g., the seat boards 402 of FIG.4).

As with gaming objects described above that include RFID tags orresonant circuits, the system is also able to detect reflectance changesof the geofence antenna of gaming objects that include a metalizedlayer. The metalized layer may be a layer of metal foil, such asaluminum foil. The metalized layer may have a number of advantages overa resonant circuit, yet the system is still able to detect changes inreflectance of the geofence antenna due to coupling by the metalizedlayer. These advantages may include being less expensive than a resonantcircuit, being thinner than a resonant circuit, being structurally moreflexible than a resonant circuit, or having less weight than a resonantcircuit.

FIG. 11 is a flowchart of a method 1100 of detecting events in a gamingenvironment. The method 1100 may be performed by the system 100 (seeFIG. 1), 300 (see FIG. 3), etc. For example, the computer 110 (seeFIG. 1) may execute a computer program that controls the components ofthe system 100 to perform the method 1100.

At 1102, a plurality of reflection coefficients that are associated withan antenna positioned on a gaming table are detected. For example, thenetwork analyzer 106 (see FIG. 1) may detect the reflection coefficientsassociated with one of the antennas 122 (e.g., a geofence antenna). Thereflection coefficients change as an object interacts with the antenna.For example, a gaming object that includes a metalized layer or aresonant circuit may couple with or decouple from the geofence antenna,which changes the reflection coefficients.

At 1104, a game state related to the gaming table in the gamingenvironment is controlled in response to the change in the plurality ofreflection coefficients. For example, when the dealer moves a gamingobject across the geofence antenna 644 (see FIG. 6), the computer 110(see FIG. 1) changes a game state related to the gaming table 120. Theflow may then return to 1102.

The system (e.g., 100 of FIG. 1) may implement both the method 1100 ofFIG. 11 as well as the method 1000 of FIG. 10. For example, the systemmay implement the method 1000 with the spot antennas 640 (see FIG. 6),and may implement the method 1100 on the geofence antenna 644 (see FIG.6).

Speed and Power Summaries

In general, the network analyzer (e.g., 106 in FIG. 1) takes between 0.1and 0.3 milliseconds to scan one of the antennas (e.g., 122 in FIG. 1),and the RFID reader (e.g., 108 in FIG. 1) takes between 5 and 500milliseconds to read the RFID tags at that antenna. The large variationin time for the RFID reader is due to response collisions by the RFIDtags, so reading 1 tag takes 5 milliseconds and reading 60 tags takes500 milliseconds. Thus, using the network analyzer allows forsignificant improvement in overall system read time, since the RFIDreader need not spend the 5 milliseconds to determine there are no RFIDtags present at a particular antenna.

In general, the network analyzer uses between 0.8 and 1 milliwatts toscan one of the antennas, and the RFID reader uses between 1000 and 2000milliwatts to read the RFID tags at that antenna. Thus, using thenetwork analyzer allows for significant improvement in overall systempower usage, since the RFID reader need not spend the power to readantennas that have no tags.

Detecting a Human Hand

The following sections describe implementations that use a networkanalyzer to detect the movements of a human hand. The details areotherwise similar to those described above.

One of the important parameters when designing an RF system is theantenna match. Specifically, maximum radiated power is achieved when theantenna is matched to the driving impedance. Thus, great effort isexpended to insure a good impedance match between the driver and theantenna. A perfect match results in no reflected power from the port ofthe antenna back to the driving circuitry. Thus, it is common in theindustry to use reflected power as a gauge of how well one has matchedthe driver to the antenna.

The systems discussed herein exploit this characteristic by monitoringreflected power—in real time—to detect transient perturbations inantenna impedance. Specifically, when an object (such as a hand or otherhuman appendage) is placed in the magnetic field of a driven antenna,the impedance of the antenna is disturbed and a portion of the energy isnow reflected back. A directional coupler can then be used to separatethe forward power to the antenna from the reflected power from theantenna (see, e.g., the directional coupler 864 in FIG. 8). By setting abaseline reflection coefficient when no appendage is present andcomparing it to a transient reflection coefficient above a noisethreshold, one can detect hand motions proximal to the antenna. Inpractice, sensing both the amplitude and the phase of the reflectedsignal (typically in the form of I and Q—the real and imaginary parts ofthe reflected signal) allows the system to detect these hand motions.

RFID systems at 13.56 MHz use the magnetic field to couple the antennato one or more tags in the excitation field. A high magnetic field isachieved by having a high Q antenna (one that is narrowly matched at theoperating frequency).

Using the same 13.56 MHz antenna for sensing of the hand as is used forthe RFID simplifies the overall system. 13.56 MHz is a frequency that isallowed higher power levels by the Federal Communications Commission(FCC), making it a good choice of frequency for both RFID and sensing ofhand motion. The system to detect the appendage can have good filtering,as the appendage moves slowly relative to the speed of the RF system(which is only limited by the antenna bandwidth).

In one embodiment, an antenna with a Q of 100 gives good detectioncapability. The Q determines the system bandwidth, and a Q of 100provides a 136 KHz of bandwidth. With this bandwidth it is possible todetect events as quick as 10 microseconds (usec), which is far greaterthan any motion of a human hand.

The power reflected from the antenna can be represented as I and Qvalues on a unit circle, where a fully reflected signal would be plottedas a point on the circumference of the circle (the location on thecircumference determined by the phase) and a perfectly matched antennawould have 0 reflected power and be represented by a point in the centerof the circle. In practice, the antenna match will not be perfect, butwill be somewhere near the center.

Embodiments exploit the displacement of I and Q values when a hand (orother device) perturbs the field.

FIG. 12 is a block diagram of a detection system 1200. In general, thedetection system 1200 is a component of a gaming table. The detectionsystem 1200 is similar to the other systems described herein (e.g., thesystem 100 of FIG. 1, the seat board 600 of FIG. 6, etc.). However, thedetection system 1200 also includes the capability to detect hand (orother appendage) movements, and to use that information to control thegame state. The detection system 1200 includes an antenna 1202, an RFIDreader 1204, a network analyzer 1206, a control device 1208, and aswitch 1210.

The antenna 1202 is a single loop antenna that operates at 13.56 MHz andhas a Q of around 100, as discussed above. The antenna 1202 is placed onthe gaming table (see, e.g., the gaming table 120 of FIG. 1). Theantenna 1202 may be on a seat board (see, e.g., the seat board 402 a ofFIG. 4). The antenna 1202 may be one of a number of similar antennas onthe gaming table. In general, the antenna 1202 is related to a bettingspot, or other type of game action area, in which RFID tags or handmotions are to be detected. The placement of the antenna 1202 on thegaming table may be adjusted as desired. The antenna 1202 may be aprinted circuit board antenna with a length of 9 inches and a width of 2inches. These dimensions may be adjusted as desired to increase ordecrease the area to be monitored. For example, the antenna 1202 may betrapezoidal in shape, or otherwise shaped to fit within defined areas ofthe gaming table. The antenna 1202 has one end connected to the switch1210 and another end connected to ground.

The RFID reader 1204 energizes the antenna 1202 to read RFID tags (e.g.,in gaming chips) in the vicinity of the antenna 1202. In general, theRFID reader 1204 energizes the antenna 1202 with sufficient energy suchthat RFID tags inside the antenna 1202 (up to a height of about 6 inchesabove the gaming table) are read, and RFID tags outside of the antenna1202 are not read. Otherwise the RFID reader 1204 is similar to theother RFID readers discussed herein (e.g., the RFID reader 108 of FIG.1, the RFID reader 408 a of FIG. 4, etc.). The RFID reader 1204 iscontrolled by the control device 1208, and sends the RFID information itreads from the RFID tags to the control device 1208.

According to one embodiment, the RFID tags are highly tuned with a highQ.

According to another embodiment, the RFID tags have a ferrite core, e.g.as described in U.S. Application Pub. No. 2009/0179741. These ferritecore RFID tags are detuned, with a lower Q than RFID tags lacking theferrite core. However, when the ferrite core RFID tags are stacked, theferrite cores carry the magnetic flux upward, increasing the detectionheight of the topmost RFID tag in the stack.

The network analyzer 1206 detects the reflection coefficient of theantenna 1202, as described in more detail in other sections of thisdocument. More specifically, the network analyzer 1206 detects changesin the reflection coefficient as a human appendage interacts with theantenna 1202. The network analyzer 1206 is otherwise similar to theother network analyzers discussed herein (e.g., the network analyzer 106of FIG. 1, the network analyzer 406 a of FIG. 4, etc.). The networkanalyzer 1206 is controlled by the control device 1208, and sends thereflection coefficients it detects from the antenna 1202 to the controldevice 1208.

The control device 1208 generally controls the operation of thedetection system 1200. The control device may be implemented as acontrol board (e.g., similar to the control board 104 of FIG. 1), as acomputer (e.g., similar to the computer 110 of FIG. 1), or a combinationof devices (such as including both a control board and a computer). Thecontrol device 1208 controls the RFID reader 1204 to perform a readusing the antenna 1202, and controls the network analyzer 1206 to detectthe reflection coefficient using the antenna 1202. The control device1208 controls which one of the RFID reader 1204 and the network analyzer1206 is connected to the antenna 1202 by sending a control signal to theswitch 1210. The control device 1208 may connect to other devices (notshown), for example via a network connection (not shown), and may sendthe information from the RFID reader 1204 and the network analyzer 1206to the other devices.

The switch 1210 selects between the RFID reader 1204 and the networkanalyzer 1206 being connected to the antenna 1202. The switch 1210 iscontrolled via the control signal from the control device 1208.

The detection system 1200 generally operates as follows. The controldevice 1208 stores a number of states that are related to the gameperformed on the gaming table. In a first example state, the controldevice 1208 monitors activity using both the RFID reader 1204 and thenetwork analyzer 1206, for example by performing 10 detections using thenetwork analyzer 1206 followed by 1 read using the RFID reader 1204. Ina second example state, the control device 1208 monitors activity usingonly the RFID reader 1204. In a third example state, the control device1208 monitors activity using only the network analyzer 1206. Thedetection system 1200 then transitions between the states according tothe game rules and detected events, such as RFID tag changes (detectedby the RFID reader 1204), hand motions (detected by the network analyzer1206), etc. For example, when the detection system 1200 is in a “waitingfor dealer to deal a card” state, the detection system 1200 transitionsto the next state upon detecting the dealer's hand interacting with theantenna 1202 (according to its changed reflection coefficient) as thedealer deals the card to a player at the gaming table.

According to an embodiment, the detection system 1200 is configured todetect hand movements within one-half inch of the antenna 1202. As thereis generally a layer of felt on the gaming table above the antenna 1202,dealers may be trained to move their hands just above the level of thefelt, or in contact with the felt (but still not in contact with theantenna 1202), in order to trigger the detection.

The arrangement of the components of the detection system 1200 may beadjusted as desired in alternative embodiments. As one option, the RFIDreader 1204 and switch 1210 may be omitted, in which case the detectionsystem 1200 operates as a geofence system (see, e.g., the geofenceantenna 644 of FIG. 6 and the method 1100 of FIG. 11). As anotheroption, the RFID reader 1204 and the network analyzer 1206 may becombined into a single device (see, e.g., the combined RFID reader andnetwork analyzer 308 of FIG. 3), in which case the switch 1210 may beomitted from the detection system 1200. As another option, the detectionsystem 1200 may be one of a number of detection systems on a gamingtable, where each antenna is associated with a different seat or bettingarea; various of the components may be combined and the signalsmultiplexed, similar to FIG. 4.

Similarly, the number of game states, and the events that triggerchanges between the game states, may be adjusted as desired inalternative embodiments. A game state may include sub-states, each withassociated events and triggers. A game state may also be associated withlocation information. For example, consider the game of Blackjack,having a Deal game state in which the dealer deals the cards to eachplayer position. (Each player position is associated with an antenna.)The Deal state includes a number of sub-states associated with thedealer's hand being detected passing over one of the antennas. Forexample, when the system detects the dealer's hand passing over theantenna for the first player position, the system knows the dealer hasdealt a card to that location. When the system detects the dealer's handpassing over the antenna for the second player position, the systemknows the dealer has dealt a card to that location. With the addition ofan instrumented shoe to read the value of the card that has been dealt,the system then computes the value of each hand dealt to each location.

FIG. 13 is a block diagram of a detection system 1300. The detectionsystem 1300 is similar to the detection system 1200 (see FIG. 12). Thedetection system 1300 includes an antenna 1302, an RFID reader 1304, anetwork analyzer 1306, a control device 1308, and a switch 1310. TheRFID reader 1304, the network analyzer 1306, the control device 1308,and the switch 1310 are respectively similar to the RFID reader 1204,the network analyzer 1206, the control device 1208, and the switch 1210of FIG. 12.

The antenna 1302 is a double loop, FIG. 8 (figure eight) antenna. Notethat at point 1320, the connections between the loops do not actuallyintersect in an X shape; one of the connections passes underneath theother on the circuit board, making a single path from the switch 1310 tothe ground connection. As compared to the antenna 1202 (see FIG. 12),the antenna 1302 constrains the magnetic flux to an area that moreclosely corresponds to the area inside the antenna 1302. Thus, theantenna 1302 is not as sensitive to appendages outside of the antenna1302, as compared to the antenna 1202.

The antennas 1202 (see FIG. 12) and 1302 (see FIG. 13) have differentdetection volumes. For the antenna 1202, the magnetic field lines aregenerally viewed as concentric cylinders around each line of the antenna1202. Or viewed cross-sectionally from the side, the antenna linesappear as two points, and the magnetic field lines form concentriccircles around each point. The density of the magnetic field lines isgreater between the lines of the antenna 1202 than outside of theantenna 1202; but since the magnetic field lines do extend outside ofthe antenna 1202, there is the potential to detect hand movementsoutside of the antenna 1202.

For the antenna 1302, the magnetic field lines are generally viewed asconcentric cylinders concentrated around the inner two lines of theantenna 1302, with only a small amount of magnetic field lines extendingoutside of the outer two lines of the antenna 1302. Or viewedcross-sectionally from the side, the antenna lines appear as fourpoints; the magnetic field lines form dense concentric ovals around theinner two points, and only a few magnetic field lines form concentriccircles around each of the outer two points. As compared to the antenna1202, the magnetic field lines of the antenna 1302 are more clearlyconstrained inside the boundary of the antenna 1302.

FIG. 14 is a polar diagram showing an example of reflection coefficientmeasurements by the detection system 1200 (see FIG. 12) when anappendage is not present. The polar diagram shows the line 1402resulting from the network analyzer 1206 measuring S11, the reflectanceof the antenna 1202. The network analyzer 1206 operates between 13.25MHz and 13.75 MHz, with point “1” corresponding to 13.25 MHz, point “2”corresponding to 13.56 MHz, and point “3” corresponding to 13.75 MHz.

FIG. 15 is a polar diagram showing an example of reflection coefficientmeasurements by the detection system 1200 (see FIG. 12) when anappendage is present. The polar diagram shows the line 1502 resultingfrom the network analyzer 1206 measuring S11, the reflectance of theantenna 1202. The network analyzer 1206 operates between 13.25 MHz and13.75 MHz, with point “1” corresponding to 13.25 MHz, point “2”corresponding to 13.56 MHz, and point “3” corresponding to 13.75 MHz.

Note the differing placement on the polar plots between the line 1402(see FIG. 14) and the line 1502. In general, the line 1502 is shiftedclockwise as compared to the line 1402. The control device 1208 maystore the set of three points of the line 1402 as the baseline set whenno appendage is present, and may store the set of three points of theline 1502 as the appendage detected set. Then as the network analyzer1206 detects the reflectance at these frequencies, the control device1208 determines whether an appendage is present by comparing thedetected values with the stored sets. For example, when all three of thedetected values are closer in rho and theta to line 1502 than to line1402, the control device 1208 determines that an appendage is present.

Detection Details

To mitigate false detections, it is important to establish the baselinevalue, to minimize noise, to establish a threshold above the noiselevel, and to ensure that shifts in I and Q (or rho and theta) due tohand motion exceed the threshold.

The noise can be reduced by averaging. In one embodiment, the reflectioncoefficients are averaged for 10 milliseconds—a time frame that is veryshort compared to hand motions. This time period may be increased inorder to further reduce transient changes in the detected reflectances.

Noise from proximal RFID systems (e.g., antennas on other boards such asin FIG. 4, multiple antennas on one board as in FIG. 6, etc.) can beminimized by offsetting the detection frequency. For example, instead oflooking for reflection coefficients at 13.56 MHz, one embodiment uses13.25 MHz and another embodiment uses 13.75 MHz. Different frequencies,or additional frequencies (e.g., four or more) may be used to providemore accurate detection results.

In one embodiment, the detection system measures the reflected I and Qlevels every 0.8 msec and compares this to a threshold which was set toa distance 0.02 of the unit circle. We measured I and Q at 3frequencies, 13.6, 13.7, and 13.9 MHz. If any of these moved by morethan the threshold, the detection system detected an appendage.

Short Term Calibration

The detection system 1200 of FIG. 12 uses one antenna 1202 for both RFIDand reflection coefficient measurements. (Other systems may also havethis feature, such as the detection system 1300 of FIG. 13, the system100 of FIG. 1, the system 300 of FIG. 3, etc.) In such a case, there isthe potential for RFID tags to be placed nearby the antenna 1202 for anextended period, for example as a bet placed for the entire duration ofa game. In such a case, the RFID tags may affect the reflectance of theantenna 1202, yet we still want to detect hand movements within thegame.

An embodiment adds a high pass filter to address this issue. The highpass filter may be added as a filtering function by the control device(e.g., the control device 1208 of FIG. 12). The filtering period may beset at, for example, 1 second. If the detection system detects a changein the reflectance of the antenna 1202, and the change remains forlonger than the filtering period, the result is not reported as a handmovement. Instead, the detection system 1200 uses the changed reflectioncoefficients as a new baseline; when a hand moves over the antenna 1202,the detection system 1200 then detects the hand motion due to a furtherchange in the reflectance from the new baseline.

Long Term Calibration

The detection system 1200 of FIG. 12 (or the detection system 1300 ofFIG. 13, etc.) may also perform recalibration of the baselinereflectances over a longer period than discussed above. The reflectanceof an antenna may change over time, for example due to temperature,humidity, etc. The system may perform this process in the background sothat it does not degrade the performance of the system. First (1), thesystem uses the RFID reader (e.g., the RFID reader 1204) to read anantenna, in order to determine that no gaming objects are coupled to theantenna. Second (2), the system uses the network analyzer (e.g., thenetwork analyzer 1206) to obtain the reflection coefficient at a firstfrequency. Third (3), the system uses the RFID reader (e.g., the RFIDreader 1204) to read the antenna again; if the RFID reader detectsgaming objects, then the reflection coefficient is discarded. Fourth(4), the system performs the steps (1)-(3) again five more times, toresult in six measurements for the baseline reflection coefficients.Fifth (5), the system discards the two measurements that are furthestaway from the current baseline, and averages the remaining fourmeasurements. Sixth (6), the system performs the steps (1)-(5) for asecond frequency. Seventh (7), the system performs the steps (1)-(5) fora third frequency. Eighth (8), the system stores this set of threereflection coefficients as the baseline for that antenna 1202.

Blackjack Example

This example refers to the detection system 1200 of FIG. 12. It is alsoapplicable to the detection system 1300 (see FIG. 13), as well as theother geofence detection systems described in other sections (e.g., thegeofence antenna 644 of FIG. 6, the method 1100 of FIG. 11, etc.). Inthis example, the Blackjack table has one antenna 1202 for each playerposition (and typically seven player positions), and another antenna1202 for the dealer position.

Blackjack is one of several table games in which players get to decidewhether or not to take extra cards. To properly track wins and losses,it is imperative to know who received what cards. Different rules applyat different points in a game. Thus it is important to define each ofthese rules by “game state” and further to define transitions from onegame state to the next.

A game of Blackjack may be divided into five states: New Game, BetsLocked, Deal, Play, and Showdown/Payout. Within the Deal state, eventssuch as Insurance and Dealer Blackjack may occur. Within the Play state,events such as Surrender, Hit, Bust, Splits, and Double Down may occur.In the Showdown/Payout state, the dealer displays the dealer's hand andthen performs seat by seat reconciliation and payout.

Within the New Game state, the detection system 1200 does not need tomonitor dealer hand motions. The control device 1208 may control theRFID reader 1204 to read, in order to monitor bet placements.

Within the Bets Locked state, the detection system 1200 does not need tomonitor dealer hand motions. The control device 1208 may control theRFID reader 1204 to read, in order to identify changes in the RFID tags(e.g., changes in the bet amounts due to chips being added, removed ormoved around) and to trigger an alert.

In the Deal state, the dealer deals 2 cards to each player according tocompletely prescribed motions; the detection system 1200 has no need tomonitor dealer hand motions. The control device 1208 may control theRFID reader 1204 to read, in order to identify changes in the RFID tags(e.g., changes in the bet amounts) and to trigger an alert.Alternatively, the detection system 1200 may monitor dealer hand motionsin order to verify that the dealer is dealing the cards in theprescribed manner (e.g., to the correct player positions, etc.).

In the Play state, the detection system 1200 monitors both the dealer'shand motions as well as the RFID tags (gaming tokens). The detectionsystem 1200 uses the network analyzer 1206 to detect the hand motions,and uses the RFID reader 1204 to read the RFID tags. When the RFIDreader 1204 detects changes in the RFID tags, the detection system 1200can generate an alert. When the detection system 1200 detects a handmotion at the antenna 1202 for a particular player position (or for thedealer position), the detection system 1200 knows that the dealer hasdealt a card to that particular player position (or to the dealerposition). By using an instrumented shoe, the detection system 1200 alsoknows which card was dealt to that particular player position (or to thedealer position).

Within the Play state, the steps below are repeated for all players atthe table. When the last player has finished all the steps within thePlay state, the dealer shows his “hole” card and Showdown/Payout begins.(The actual trigger to begin Showdown/Payout may be something else, forexample when the dealer's hand is sensed again using the antenna 1202 atthe first player position.)

For example:

-   -   Surrender: If a player made an insurance bet (typically ½ the        original bet), the detection system 1200 tracks whether the        insurance bet won or lost, and whether the dealer correctly        collected or paid out the insurance bet. If the detection system        1200 detects a dealer error when processing the insurance bet,        the detection system 1200 generates an alert.    -   Hit: If there is no change in bets, and a card is drawn, and the        hand is detected at Player #1, the detection system 1200 now        knows the value of their hand. The detection system 1200 knows        whether or not they busted or won (even though the dealer hand        will not be exposed until Showdown/Payout). The detection system        1200 also knows what “normal strategy” should be given what a        player was dealt, for example by storing strategy information in        one of the databases 130 (see FIG. 1). The ability to compare        “normal” strategy with actual player behavior is of value in        rating a player's skills.    -   Split: If a player has identical cards, and the detection system        1200 detects a second bet placed adjacent to the original bet        (as a separate bet), the detection system 1200 determines that        it must be a Split. In this case, the player will receive        additional cards (how many depends on a number of detailed        rules). Sensing dealer hand motions for each card is critical.        The detection system 1200 may infer how to assign each dealt        card to one of the two (or more) split hands.    -   Double Down: If the base bet is doubled (on the same spot as the        base bet), the player will receive a single additional card.        Monitoring hand position when dealing this single card is not        critical, but the detection system 1200 may monitor it in order        to confirm the player's decision (and to generate an alert if it        detects the card is dealt to the incorrect player position).

According to an embodiment, the detection system 1200 includes aninstrumented shoe (to determine the value of the card dealt) as well asa number of antennas 1202 (to determine where each card was dealt).Using this information and a game strategy database (e.g., stored in thedatabases 130 of FIG. 1) enables the detection system 1200 to rate theskill level of each player. The detection system 1200 also uses the RFIDreader 1204 to read the RFID tags in the gaming tokens and to determinethe value of bets placed by each player, for example by using a chipdatabase (e.g., stored in the databases 130 of FIG. 1). The detectionsystem 1200 can then use the player's strategy information and betinformation in order to determine comps earned, using a comps database(e.g., stored in the databases 130 of FIG. 1).

The Showdown/Payout state includes a logical component and a tacticalcomponent. In Showdown (logical), after the dealer reveals his “hole”card, the logical game state changes from Play to Payout. The dealerthen services each player in sequence to either (1) collect losing betsor (2) payout winning bets. This reconciliation takes place player byplayer.

In Showdown (tactical), with the dealer focused on the player he isservicing, his attention will not be on other “downstream” players. Withthe outcome of the game known, there is a temptation for some players tomove/remove their losing bets. Thus, it is desirable to transition toPayout mode “seat by seat”. In other words take the example where:

-   -   Player 1 has been serviced (losses collected; payouts made).        That player position is now in New Game state.    -   Player 2 is being serviced. The dealer hand has been detected        and Player 2 is in Payout state. All losing bets get collected        first. Payouts for each bet are in sequence. In some cases, it        is possible to tie each individual payout to each winning bet.        In the case of Blackjack, this can be difficult (chaotic payout        schemes)—but at a minimum—the detection system 1200 can project        and verify the overall net of wins/losses.    -   Players 3 through 7 have yet to be serviced. These players        remain in the Play state—where any changes in bets can trigger        alarms.    -   When the dealer's hand is detected at Player 3, the game state        for Player 2 changes from Payout to New Game, and for Player 3        changes from Play to Payout.    -   When the last player is serviced, the entire table is in New        Game state.

The above number of states may be increased or decreased as desired, inorder to adjust the granularity of monitoring performed. In a similarmanner, states may be defined for other casino games, and the rules ofthe game parsed in order to define the events that trigger changesbetween the game states, and to define the errors to detect and togenerate alerts.

FIG. 16 is a flowchart of a method 1600 of detecting events in a gamingenvironment. The method 1600 may be performed by the detection system1200 (see FIG. 12), the detection system 1300 (see FIG. 13), the system100 (see FIG. 1), the system 300 (see FIG. 3), the system 400 (see FIG.4), the system 500 (see FIG. 5), etc. For example, the control device1208 (see FIG. 12) may execute a computer program that controls thecomponents of the detection system 1200 to perform the method 1600.

At 1602, a plurality of reflection coefficients are detected. Thereflection coefficients are associated with an antenna positioned on agaming table. The reflection coefficients change as a human appendageinteracts with the antenna. For example, the network analyzer 1206 (seeFIG. 12) may detect the reflection coefficients associated with theantenna 1202. The reflection coefficients may be obtained at one or morefrequencies. As an example, the network analyzer 1206 may detect at onefrequency, and the measured reflection coefficients change from onevalue (when the appendage is not present) to another value (when theappendage is present). As another example, the network analyzer 1206 maydetect at three frequencies (see FIGS. 14-15), and one or more of themeasured reflection coefficients each change from one value (when theappendage is not present) to another value (when the appendage ispresent).

At 1604, a game state related to the gaming table in the gamingenvironment is controlled in response to the change in the plurality ofreflection coefficients. For example, the control device 1208 (see FIG.12) may control the game state in response to the change in thereflection coefficients.

In this manner, the detected hand movements may be used to control thestate of the game being performed on the gaming table.

The method 1600 may include other steps in additional embodiments. Oneadditional embodiment is as follows. First, the antenna is selectivelyenergized. For example, the control device 1208 (see FIG. 12) maycontrol the RFID reader 1204 to selectively energize the antenna 1202.Second, a plurality of identifiers of a plurality of RFID tags that arenearby to the antenna are read. For example, the RFID reader 1204 mayread the identifiers of RFID tags that are stacked on the gaming tableinside of the antenna 1202. Then, 1604 is modified such that the gamestate is controlled in response to the change in the plurality ofreflection coefficients and the plurality of identifiers. For example,if the game is in Game State 1 and only a hand movement is detected, thegame transitions to Game State 2; if only RFID tags are detected, thegame transitions to Game State 3; and if both a hand movement and RFIDtags are detected, the game transitions to Game State 4.

Another additional embodiment is as follows. First, a baseline set ofreflection coefficients are stored. For example, the control device 1208may store the baseline set in a memory (e.g., in a database). Second, anew baseline set of reflection coefficients are periodically acquired.For example, the control device 1208 may control the network analyzer1206 to detect the reflection coefficients when a game is not inprogress (e.g., between games). Third, the baseline set of reflectioncoefficients are updated with the new baseline set of reflectioncoefficients. For example, the control device 1208 may update thedatabase to reflect the new baseline set.

Another additional embodiment is as follows. The gaming table mayinclude a number of antennas, where each antenna is associated with aplayer position at the table. The system may perform the method 1600 foreach of the antennas concurrently. In this manner, the system maydiscretely track the game state (or sub-states within a game state) foreach player position.

The above description illustrates various embodiments of the presentinvention along with examples of how aspects of the present inventionmay be implemented. The above examples and embodiments should not bedeemed to be the only embodiments, and are presented to illustrate theflexibility and advantages of the present invention as defined by thefollowing claims. Based on the above disclosure and the followingclaims, other arrangements, embodiments, implementations and equivalentswill be evident to those skilled in the art and may be employed withoutdeparting from the spirit and scope of the invention as defined by theclaims.

What is claimed is:
 1. A system for detecting events in a gamingenvironment, comprising: an antenna positioned on a gaming table; anetwork analyzer device, coupled to the antenna, that is configured todetect a plurality of reflection coefficients that are associated withthe antenna, wherein the plurality of reflection coefficients change asa human appendage interacts with the antenna; and a control device,coupled to the network analyzer device, that is configured to control agame state related to the gaming table in the gaming environment inresponse to the change in the plurality of reflection coefficients. 2.The system of claim 1, wherein the plurality of reflection coefficientschange from a first state to a second state when the human appendagemoves from outside the antenna to inside the antenna.
 3. The system ofclaim 1, wherein the plurality of reflection coefficient change from asecond state to a first state when the human appendage moves from insidethe antenna to outside the antenna.
 4. The system of claim 1, whereinthe plurality of reflection coefficients change from a first state to asecond state when the human appendage moves from outside the antenna toinside the antenna, wherein the plurality of reflection coefficientchange from the second state to the first state when the human appendagemoves from inside the antenna to outside the antenna, and wherein thecontrol device controls the game state according to the plurality ofreflection coefficients switching between the first state and the secondstate.
 5. The system of claim 1, wherein the human appendage interactswith the antenna by passing over the antenna on the gaming table.
 6. Thesystem of claim 1, wherein the plurality of reflection coefficientschange as the human appendage and an object interact with the antenna,wherein a gaming object includes the object.
 7. The system of claim 1,further comprising: a radio frequency identification (RFID) readerdevice that is configured to selectively energize the antenna and toread a plurality of identifiers of a plurality of RFID tags that arenearby to the antenna, wherein the control device is configured tocontrol the game state in response to the change in the plurality ofreflection coefficients and the plurality of identifiers.
 8. The systemof claim 1, wherein the antenna has a single loop shape.
 9. The systemof claim 1, wherein the antenna has a single loop, rectangular shape.10. The system of claim 1, wherein the antenna has a double loop shape.11. The system of claim 1, wherein the antenna has a double loop, figureeight shape.
 12. The system of claim 1, wherein the control devicestores a baseline set of reflection coefficients, wherein the controldevice periodically controls the network analyzer to acquire a newbaseline set of reflection coefficients, and wherein the control deviceupdates the baseline set of reflection coefficients with the newbaseline set of reflection coefficients.
 13. The system of claim 1,wherein the network analyzer device operates between 13 and 14 MHz. 14.The system of claim 1, wherein the game state is one of a plurality ofgame states, wherein the antenna is one of a plurality of antennaspositioned on the gaming table, wherein the plurality of antennas arerespectively associated with a plurality of locations, and wherein thecontrol device is configured to associate each of the plurality oflocations with a corresponding one of the plurality of game states inresponse to the change in the plurality of reflection coefficients for acorresponding one of the plurality of antennas.
 15. A method ofdetecting events in a gaming environment, comprising: detecting aplurality of reflection coefficients that are associated with an antennapositioned on a gaming table, wherein the plurality of reflectioncoefficients change as a human appendage interacts with the antenna; andcontrolling a game state related to the gaming table in the gamingenvironment in response to the change in the plurality of reflectioncoefficients.
 16. The method of claim 15, further comprising:selectively energizing the antenna; and reading a plurality ofidentifiers of a plurality of RFID tags that are nearby to the antenna,wherein controlling the game state comprises controlling the game statein response to the change in the plurality of reflection coefficientsand the plurality of identifiers.
 17. The method of claim 15, furthercomprising: storing a baseline set of reflection coefficients;periodically acquiring a new baseline set of reflection coefficients;and updating the baseline set of reflection coefficients with the newbaseline set of reflection coefficients.
 18. A method of detectingevents in a gaming environment, comprising: detecting a plurality ofreflection coefficients that are associated with a plurality of antennaspositioned on a gaming table, wherein the plurality of antennas arerespectively associated with a plurality of locations on the gamingtable, and wherein the plurality of reflection coefficients change as ahuman appendage interacts with the plurality of antennas; andcontrolling a plurality of game states related to the gaming table inthe gaming environment in response to the change in the plurality ofreflection coefficients, wherein each of the plurality of locations isassociated with a corresponding one of the plurality of game states inresponse to the change in the plurality of reflection coefficients for acorresponding one of the plurality of antennas.